Axially and radially air bearing support



Mal ch 12, 1968 CARTER 3,373,414

AXIALLY AND RADIALLY AIR BEARING SUPPORT Filed May 6, 1963 2Sheets-Sheet 1 INVENTOR. DONALD L. CARTER March 12, 1968 D. L. CARTER3,373,414

AXIALLY AND RADIALLY AIR BEARING SUPPORT Filed May 6, 1963 2Sheets-Sheet 2 FIG.3

United States Patent 3,373,414 AXIALLY AND RADIALLY AIR BEARING SUPPORTDonald L. Carter, Vestal, N.Y., assignor to International BusinessMachines Corporation, New York, N.Y., a corporation of New York FiledMay 6, 1963, Ser. No. 278,130 16 Claims. (Cl. IMO-174.1)

The invention relates generally to a magnetic storage memory assemblyfor use with a computer, and more particularly to a magnetic drummemory.

In data processing equipment, such as computers, it is usual to provideone or more data storage units, one important general type of which iswhat is termed a magnetic drum memory. Information to be stored istransferred to and read from a drum, or cylindrically, shaped magneticmember through the instrumentality of magnetically operated transducingheads (reading and/or writing heads). It is inherent in the operation ofmagnetic drum memories that a slight space be maintained between themagnetic storage member and the heads, and access to the differentportions of the magnetic storage member is achieved by a combination ofrotating the member about its cylindrical axis and positioning the headslongitudinally along this axis.

Important to efiicient operation of drum memories is the requirement tomaintain the heads in a uniform, closely spaced arrangement (usuallywithin several tenths of a thousandth of an inch) to the magnetic drumthroughout reading and writing. This has been obtained in certain priorart devices by journaling the rotatable drum in high quality bearingraces and fixedly securing the heads adjacent. Due to such things aseccentricities, warpage, creep, and the like, these devices have notbeen found to be fully satisfactory and certain other known drummemories maintain the continuous uniform spacing arrangement of theheads by supporting the heads on a film of air, or other gas, which isformed as a result of the rapid rotation of the drum cylinder past theheads.

Various problems are associated with drums having fluid mounted, orfloated heads as they are sometimes called. First of all, there is thenecessity for providing auxiliary means to hold the heads spaced fromthe record ing surface during periods when the drum is at rest orrotating at a rate insufficient to generate a supporting film of air. Ifthis is not done damage would result to the heads and/ or recordingsurface. Additionally, further means are required to keep the mutualspacing arrangement of'the heads and recording surface uniformthroughout operation in order that consistent reading and writing isobtained. It is also implicit that failure of such head spacing devicescan also result in inaccuracies of reading and writing and thereby canbe considered to adversely aiTect the reliability of a drum memory aswell as increase its cost.

It is therefore a primary object and purpose of the present invention toprovide a magnetic drum memory in which reading and writing heads are atall times maintained in a non-contacting relation to the recordingmember.

Another object of the invention is the provision of such a drum memoryhaving a complete gas bearing mounting for the rotatable member.

A further object of the invention is the provision of such a memoryhaving a hysteresis impulse drive system.

A still further object of the invention is the provision of a drummemory in which the rotatable recording member is completely supportedin all directions by a laminar fluid boundary during operation.

Another object is the provision in a drum memory of means for protectingthe storage member during starting, stopping and quiescence.

A still further object of the present invention is to provide a drummemory of the type referred to in the above objects which ischaracterized by its low cost and extreme simplicity.

Briefly, the present invention provides a magnetic drum memory having agenerally cylindrical recording member contained within a similarlyshaped support housing. A hysteresis drive assembly included within themember serves to rotate it Within the housing in a spaced relation toadjacent structures by means of gas laminar bearing action. Reading andWriting heads are fixedly mounted Within the supporting housing withmutual spacing of the heads and recording member being predetermined bythe dimensions of the supporting structure relative to the recordingmember.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings.

In the drawings:

FIGURE 1 is an exploded view of the different component parts of a drummemory made in accordance with the practice of the invention.

FIGURE 2 is a sectional, fragmentary view of a part of the device shownin FIGURE 1 taken along the line 2-2.

FIGURE 3 is a sectional, partly fragmentary view of the invention ofFIGURE 1 in assembled condition.

FIGURE 4 illustrates a greatly enlarged fragmentary portion of one formof recording member for practicing the invention.

FIGURE 5 is another structural embodiment of a recording member.

With reference now to FIGURES 1 and 3, and particularly FIGURE 1, themagnetic drum memory of the invention is seen to comprise in its majorelements a hollow cylindrical body 10, a similarly shaped recordingmember 11 for being received within the body It), an impulse drivingelement .12 received within the recording member 11 and end plates 13and 14 serving to enclose and maintain the entire assembly as anintegral unit.

As particularly shown in FIGURE 2, the relative dimensions of the cavityof the body 10 and the general outer diameter of the recording member 11are such that the member 11 can be included within the body in a veryslightly spaced arrangement. When the member is set into rotative motionabout its cylindrical axis the air, or other gas, disposed between theouter surface of the recording member and the inner opposed wall of thebody 10 serves as a bearing. It is also a feature of this device that inaddition to the radial fluid support of the recording member, a similarfluid bearing condition exists at the extremities of the member suchthat longitudinal spacing is obtained between the ends of the member 11and the end plates 13 and 14. Accordingly, when the member 11 is broughtup to full rotational speed through the influence of the driving element12 a fluid boundary exists in full surrounding relation to the recordingmember leaving it supported throughout operation and thereby effectingan exceptionally low friction drive.

Magnetic transducing heads 15 for reading and/ or writing information inconnection with the recording member are received in appropriatelyshaped openings 16 of the body 10. The exact number and relativepositions of the different heads are dependent upon the nature of useand number of information channels to be provided on the recordingmember.

In general assembled condition (FIGURE 3) it is contemplated that therecording member 11 is of such dimensions as to be able to be rotated bythe electromagnetic action of the driving element 12 in a freenon-contacting relation with respect to the driving element, body 10 oreither of the end plates. In a way that will be brought out more clearlylater, rotation of the member in such manner at a high rate of speedresults in its floating on a cushion of air completely free ofmechanical connection of any kind.

As to structural details of the body 10, it comprises a generallycylindrically shaped body constructed of a metallic material having goodrigidity characteristics and being relatively non-magnetic. The innersurface 17 is accurately formed to permit rotation of the member 11therein while maintaining a radial spacing between the two which is lessthan 0.001 of an inch. That is, the cavity of body 10 must be a truecylinder to within the required degree of accuracy and free fromexcessive ellipticity. The end walls 18 are faced to form single planesurfaces normal to the cylindrical axis of the body 10, and are providedwith threaded openings 19 for a purpose that Will be described later.

Also, as noted, a plurality of openings 16 are formed in the body 10 forreceiving transducers 15. The operating portions, or faces, 20 aredisposed and maintained coplanar with the surface 17 through theinstrumentality of a suitable adhesive material or cement 20'. Inactuality, the heads are initially cemented within the openings 16 withthe faces 20 extending slightly into the cavity of the body 10. Theinner surface 17 and operating faces 20 are then machined together as aunit so that the faces conform and are continuous with the inner surfaceof the body 10. Thus, the heads are an integral part of the body 10 inwhich they are fixedly mounted, and do not require auxiliary apparatusfor positioning, but rather depend upon proper dimensions of thefinished body 10 to obtain correct spacing relative to the member 11.

The only moving part in the drum memory is the recording member 11 whichis of a generally hollow cylinder geometry. It is important to noteinitially that each of the two illustrated embodiments of the member 11in FIGURES 4 and provide a recording medium, an air bearing cylindricalsurface, air bearing thrust runners, a hysteresis motor rotor and wearresistant surfaces for protection of the recording medium duringstarting and stopping.

As to the detailed structural aspects of the embodiment shown in FIGURE4, it includes a pair of generally disc like collars 21 constructed of amaterial having the appropriate magnetic characteristics to make itsuitable for use as a hysteresis impelled rotor. A satisfactory materialfor this purpose is cobalt steel which not only has a relatively highhysteresis loss, but also is hard and durable providing an importantfunction that will be expanded upon later. Also, such a material shouldnot have an adverse magnetic coaction with etiher the heads 15 or therecording medium.

These collars have hubs 22 which are pressed into a receiving cavity ofa sleeve 23 of hollow cylindrical geometry, in a tight-fittingfrictionally engaged relation. An excellent material for this sleeve isberyllium which combines the desirable properties of lightness of weightand of being relatively non-magnetic. Also, beryllium has a thermalcoefficient of expansion closely approximating that of cobalt steel sothat even relatively great changes in environmental temperature do noteffect a loosening of the press fit of these parts.

A layer 24 of copper is plated onto the outer, or peripheral, portionsof the sleeve 23. The layer is then machined to provide a cylinder ofprecise external dimensions substantially free from ellipticity. Thislayer serves as a substrate over and on which there is deposited byconventional electroplating techniques a coating 25 of a nickel-cobaltalloy, which coating acts as a magnetic storage medium in that localizedportions can be set to specified magnetic states by controlling magneticfields and these states will remain until they are affirmativelychanged. Reading and writing of such magnetic states are accomplished bymagnetic heads 15 previously described.

A second form or embodiment of the recording member 11 which can beadvantageous particularly from the standpoint of ease of fabrication, isthat illustrated in FIGURE 5. The overall construction is similar to thefirstdescribed embodiment of FIGURE 4 with the primary change being thedetails of the hysteresis runners or collars. More explicity, thisembodiment of the recording member 11 comprises a hollow cylindricalbase 26 over which there is provided a sleeve 27 of identical physicalcharacteristics to the sleeve 23. As before, a layer 28 of copper isdeposited over the sleeve 27 and finished to form a highly accuratecylinder substantially free of ellipticity. A film 29 of a magneticmaterial, such as a nickel-cobalt alloy, is provided over the copperlayer to serve as the recording medium. As shown, the length andrelative disposition of the sleeve 27 to the base 26 are such that theextremities of the sleeve lie inwardly of the extremities of the base.Similarly, the layer 28 and film 29 both terminate longitudinallyinwardly of the extremities of the sleeve.

A pair of special collars 30 each having a generally disclike body andan inwardly directed hub 31 are provided of such dimensions as to bereceived over and onto the extended parts of the base 27. Also, the hub31 of each collar fits over the protruding portion of the sleeve 27 andabuts against the extremity of the layer 28 and film 29. As before, thecollars extend radially slightly beyond the outermost parts of therecording film to serve the protective purpose which is a primary objectof the invention. Material requirements for the collars 30 are the sameas for the collars 21.

It is important that the spacing a, of FIGURE 3, between the heads 15and the film 29 (or coating 25, as the case may be) be uniform and keptto a small dimension. Accordingly, this requires the dimension b, (c.f.FIGURE 4, for example) the radial difference between the outermostsurface of the recording medium and the periphery of the collars, becommensurately small. Indicating the degree of size referred to, in anactual constructed embodiment of the invention the dimension b was 50micro-inches (0.000050 inch). In this manner full protection is affordedthe magnetic memory film or coating from either accidental physicalcontact during operation or contact that would normally be expectedduring starting or stopping, and this is accomplished withoutsacrificing the reading and writing advantages gained by maintaining theclose spatial arrangement of the heads and memory medium.

Referring now again to FIGURE 1, with the recording member 11 containedwithin the cavity of the body 10 the impulse driving element 12 islocated within the member 11. The element 12 is structurally similar toa motor, or generator, armature in that it has a plurality of windings,shown collectively at 32, centrally and fixedly disposed on a shaft 33.When fully mounted the end plates 13 and 14 are secured to the end faces18 of the body 10 by threaded members 34 and have centrally alignedopenings for receiving the ends of the shaft 33 therethrough. By meansof nuts 35 the driving element is firmly secured to and held immovablewith respect to the end plates and body 10. The relative dimensions andpositioning of the element 12 in regard to the member 11 and body 10 aresuch that at no time can any part of the member 11 come into contactwith either the windings 32 or shaft 33 of the driving element.Functionally, multiphase voltage from a suitable source (not shown) isapplied to the Windings to provide a rotating magnetic field about theelement 12 with the shaft 33 as an axis. The field, in turn, inducescorresponding electric currents in the collars 21, 27 which causes thecollars and entire member 11 to rotate forming what is sometimesreferred to as a hysteresis motor. Exemplary of operations of a drum ofthis sort, in an actual run with six (6) watts of driving power arecording member was driven at 8000 revolutions per minute, which iswell above normal present day requirements for drum memories.

Although no special surface treatment of either the magnetic recordingmedium or opposed inner surface 17 of the body 10 is necessary to effectan air bearing between these surfaces, special measures are needed todevelop thrust air-bearing forces, that is, along directions parallel tothe axis of the member 11. The particular means for achieving this areshown in various views in FIGURES 1, 2, 3 and 5, and are seen tocomprise fluid shearing grooves 36 formed in a generally spiralarrangement symmetric about the center of each end plateand on thesurfaces directed inwardly, or toward, the driving element 12. Morespecifically, the set of grooves on each end plate spiral in a commondirection, which direction is such that the rotating member 11 turnsinto, or moves into, the convex portion of the grooves first. Thus, asshown in FIGURE 1 the correct motion of the member 11 with respect tothe end plate 14 is counter clockwise as viewed into the end of themember closest to the viewer. As the collars 21, 30 of the member moverapidly past the grooves air is driven into the different grooves wherea shearing action occurs resulting in an outward thrusting action of theair away from the end plates and exerted against the collars. In view ofthe highly symmetrical character of the end plates, collars on themember 11 and the body 10 substantially equal fluid thrust forces aregenerated at each collar serving to provide a fluid bearing at each endof the member. Air is supplied from the exterior to the interior of thedrum memory via openings 37 in the plates.

In summary of operation, when no energization voltage is applied therecording member 11 is at rest, or, more exactly, the collars are inbearing contact with the lower inner surface 17 of the body 10. Therealso may be bearing contact of the collars and the inner face of one ofthe end plates, depending on the orientation of the device. Applicationof driving power causes the member 11 to begin to rotate and when itreaches a certain velocity, dependent on the physical features of thedevice, cushions of supporting air will be formed over the peripheralcurved portions and end portions as previously described.Again, onslowing down When driving power is removed the supporting effect of theair films is reduced until the collars come into bearing contact withadjacent opposed surface areas of the body 10.

A drum memory constructed in accordange with the present inventionpossesses a number of advantages over known drum memories havingconventional bearing jour nals for the rotating parts. The most obvious,and beneficial, is the considerable reduction in frictional dragafforded by the use of a complete air-bearing system. With thiselimination of bearing drag there is a consequent reduction inelectrical driving power requirement which is reflected by cooleroperation and may in some cases be determinative of use wheretemperature restrictions are crucial.

A further incidental advantage of the invention is the elimination ofproblems associated with contamination from lubricants that wereformerly used with conventional bearing races. Elimination of lubricantshas permitted the increase in radiation resistance thereby increasingthe area of environmental acceptance for the invention.

In providing a drum memory device that does not require means forlifting the heads from operative relation to the storage medium as iscustomary in certain known structures a substantial reduction in thenumber of moving parts is afforded with a concomitant improvement inreliability. This is particularly true in fabricating where the fewernumber of parts means less chance of contamination during assembly.

While the invention has been particularly shown and 6 described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formand details may be made therein without departing from the spirit andscope of the invention.

What is claimed is:

1. In a magnetic information storage assembly having a support body, amagnetic storage member within said support body, means for rotating thestorage member relative to said body, the improvement comprisingself-acting gas bearing means for axially and radially supporting thestorage member in non-contacting relationship with respect to saidsupport body during the rotation of said magnetic storage member.

2. A magnetic storage drum comprising:

a magnetic storage member;

a second member comprising a base having walls defining a cavity forreceiving the storage member therein in enclosed relation;

drive means associated with the storage member for effecting rotation ofthe storage member relative to the base, said rotation of the storagemember effecting a self-acting fluid bearing condition adjacent theperipheral portions thereof to support axially and radially the storagemember in a spaced condition to said base.

3. A magnetic storage drum as in claim 2, wherein said drive meanscomprises a hysteresis impelling stator element disposed within thestorage member, and said storage member further comprises a hysteresisrotor element operatively associated with said stator element.

4. A magnetic storage drum as in claim 2, in which said storage membercomprises a generally cylindrical body having a magnetic layer on themajor outer periphery and certain portions of said cylindrical bodybeing of slightly larger diameter than the main body portion, saidcertain portions being constructed of a relatively hard durable materialwhereby the magnetic layer is held spaced from the base by said certainportions.

5. A magnetic memory drum, comprising:

an elongated hollow cylindrical sup ort housing having open ends;

a hollow cylindrical magnetic recording member for being received withinsaid housing in a slightly spaced manner;

hysteresis drive means disposed within the recording member for rotatingthe same;

end walls enclosing the cylindrical housing; and

wherein the relative spacing of the housing member and drive means withrespect to the storage member are such that upon rotation of the membera film of air is formed over the peripheral portions thereof serving toform a complete self-acting air bearing mounting for radially supportingsaid recording member with resect to said elongated housing and foraxially supporting said recording member with respect to said end wallsduring the rotation of said recording member.

6. A magnetic memory drum comprising:

an elongated hollow cylindrical support housing having open ends;

a hollow cylindrical magnetic recording member for being received withinsaid housing in a slightly spaced manner;

hysteresis drive means disposed within the recording member for rotatingthe same;

end Walls enclosing the cylindrical housing; and

wherein the relative spacing of the housing member and drive means withrespect to the storage member are such that upon rotation of the membera film ofair is formed over the peripheral portions thereof serving toform a complete self-acting air bearing mounting for the member, andwherein further the ends of said recording member are enlarged radiallyto provide a protection means against physical contact with therecording portions of the recording member during periods when themember is rotating at rates insufiicient to generate the supporting airfilm.

7. A magnetic storage assembly, comprising:

magnetic storage body having an axis of symmetry;

a housing including a cavity of suitable dimensions for including themagnetic body therein in spaced relation to the walls defining thecavity;

multiphase field generating means mounted adjacent the magnetic body forinducing rotation of said body about its axis of symmetry;

bumper means associated with said magnetic body for preventing contactof said body with the walls of the housing defining the cavity; andself-acting gas bearing means for axially and radially supporting saidbody with respect to the walls of said housing during said rotation ofsaid body.

8. A magnetic storage assembly as in claim 7, in which the body includesa cylindrical shell of a nicke-cobalt alloy.

9. A magnetic storage assembly, comprising:

a magnetic storage body having an axis of symmetry;

a housing including a cavity of suitable dimensions for including themagnetic body therein in spaced relation to the walls defining thecavity;

multiphase field generating means mounted adjacent the magnetic body forinducing rotation of said body about its axis of symmetry;

means restricting air flow into and out of the cavity;

and

bumper means associated with said magnetic body for preventing contactof said body with either the walls of the housing defining the cavity orthe restricting means, said bumper means including a plurality ofdisc-like collars of a hard durable material carried by the body, thedimensions of said collars exceeding the diametric dimensions of saidbody and having portions projecting outwardly and away from said bodyforming a protective measure against physical contact of the body andhousing.

10. A magnetic storage assembly, comprising:

a housing including walls defining a cavity therein;

a magnetic storage member of dimensions less than the cavity and locatedwithin said cavity;

electromagnetic field inducing means mounted adjacent to and for causingsaid member to rotate within said cavity relative to the housing; and

in which the storage member includes a hollow nonmagnetic cylindricalbase, a cylindrical coating of magnetic material over said base servingas a storage medium, and disc-like members received over the ends of thebase of diameters exceeding that of the base and coating serving toinsure maintaining a spaced condition between the magnetic coating andthe housing walls defining the cavity.

11. A magnetic storage assembly as in claim 10, in which the magneticcoating is a nickel-cobalt alloy and the disc-like members areconstructed of cobalt steel.

12. A magnetic storage assembly as in claim 10, in which said disc-likemembers are each provided with hublike portions that fit over andenclose portions of the extremities of the cylindrical base.

13. A magnetic storage assembly as in claim 10, in which the cavity insaid housing is of open-end cylindrical geometry slightly larger thanthe base including magnetic coating and disc-like members; and

in which there is further provided end plates in covering relation tothe open ends of the cavity, said plates including air shear-inducinggrooves for generating thrust forces against the extremities of the baseduring rotation.

14. A magnetic storage assembly as in claim 10, which further comprisesmagnetic transducing heads immovably secured to the housing andmagnetically associated with the recording coating.

15. A magnetic storage drum according to claim 2 further comprisingsolid bumper member means disposed between said magnetic storage memberand said base member for preventing contact therebetween.

16. A magnetic storage assembly, comprising:

a housing member including walls defining a cavity therein;

a magnetic storage member of dimensions less than the cavity and locatedwithin said cavity, said storage member including a hollow non-magneticcylindrical base, a cylindrical coating of magnetic material over saidbase serving as a storage medium;

means mounted adjacent to said storage member for causing said member torotate within said cavity relative to the housing; and

solid bumper member means disposed between the housing walls definingthe cavity and the storage member to insure maintaining a spacedcondition between the magnetic coating and said housing walls.

References Cited UNITED STATES PATENTS 2,602,632 7/1952 Serduke et a1340174.1 2,683,038 7/1954 Saliba et al. 179-100.2 2,854,298 9/1958Baumeister 340174.1 3,001,850 9/1961 Marrs 340-1741 3,029,416 4/1962Quade 340-174.1 3,063,041 11/1962 Quade et al. 340-1741 3,134,969 5/1964Taft 340-1741 3,248,737 4/1966 Thomas et al 179100.2

BERNARD KONICK, Primary Examiner,

V. P. CANNEY, Assistant Examiner.

1. IN A MAGNETIC INFORMATION STORAGE ASSEMBLY HAVING A SUPPORT BODY, AMAGNETIC STORAGE MEMBER WITHIN SAID SUPPORT BODY, MEANS FOR ROTATING THESTORAGE MEMBER RELATIVE TO SAID BODY, THE IMPROVEMENT COMPRISINGSELF-ACTING GAS BEARING MEANS FOR AXIALLY AND RADIALLY SUPPORTING THESTORAGE MEMBER IN NON-CONTACTING RELATIONSHIP WITH RESPECT TO SAIDSUPPORT BODY DURING THE ROTATION OF SAID MAGNETIC STORAGE MEMBER.